Horizontal directional drilling system and method

ABSTRACT

A horizontal directional drilling method includes operation of a HDD machine to power a drill string terminating at a drill head to create an underground borehole extending at least partially horizontally between an entry point and an exit point. A utility line and a pair of insulated wires are attached to the drill string at the exit point. An observation device is also attached to the drill string, and the observation device is connected with an uphole module via power line communication (PLC) over the pair of insulated wires. The horizontal directional drilling machine performs a pullback of the drill string, with the utility line, the pair of insulated wires, and the observation device connected thereto, back toward the entry point. Data from the observation device are displayed on the uphole module during pullback of the drill string.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/964,267, filed Jan. 22, 2020, the entire contents of which areincorporated by reference herein.

BACKGROUND

The invention relates to horizontal directional drilling (HDD) systemsthat are configured to drive a drill rod string into the ground fortrenchless underground utility installation. Although HDD systems allowsteering of the drill head to avoid creating crossbores with existingunderground utility installations, crossbores may be created when HDDdrilling is performed in an area with an unknown existing undergroundutility installation. Confirming that crossbores have not been createdby the new HDD drill bore can be burdensome, leading to increased jobtime and cost.

SUMMARY

In one aspect, the invention provides a horizontal directional drillingmethod. A horizontal directional drilling machine is operated to power adrill string terminating at a drill head to create an undergroundborehole extending at least partially horizontally between an entrypoint and an exit point. A utility line and a pair of insulated wiresare attached to the drill string at the exit point. An observationdevice is also attached to the drill string, and the observation deviceis connected with an uphole module via power line communication over thepair of insulated wires. The horizontal directional drilling machineperforms a pullback of the drill string, with the utility line, the pairof insulated wires, and the observation device connected thereto, backtoward the entry point. Data from the observation device are displayedon the uphole module during pullback of the drill string.

In another aspect, the invention provides a horizontal directionaldrilling system including a horizontal directional drilling machine anda drill string terminating at a drill head and configured to be drivenby the horizontal directional drilling machine to create an undergroundborehole extending at least partially horizontally between an entrypoint and an exit point. An adapter assembly is configured to couple autility line and a pair of insulated wires to the drill string. Anobservation device is configured to be attached to the drill string. Anuphole module is connected with the observation device via power linecommunication over the pair of insulated wires.

In yet another aspect, the invention provides a horizontal directionaldrilling system including a horizontal directional drilling machine anda drill string terminating at a drill head and configured to be drivenby the horizontal directional drilling machine to create an undergroundborehole extending at least partially horizontally between an entrypoint and an exit point. A camera is provided within an adapter assemblythat couples a utility line to the drill string for installation of theutility line into the borehole during pullback of the drill string, andthe camera is oriented to view in a direction opposite a direction ofthe pullback of the drill string. An uphole module is connected with thecamera via power line communication over a pair of insulated wires. Thepower line communication utilizes at least one direct burial tracer wirethat is connected to the drill string to extend along the utility lineduring pullback.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a horizontal directional drillingoperation.

FIG. 2 is a schematic view of a video monitoring system for horizontaldirectional drilling, according to one embodiment of the presentdisclosure.

FIG. 2A is a cross-section of a two-conductor tracer wire including twoisolated conductors within a common sheath.

FIG. 3A is a schematic process view illustrating a first step in anexemplary method of using the video monitoring system of FIG. 2 toidentify a crossbore during utility line installation.

FIG. 3B is a schematic process view illustrating a second step of theexemplary method of using the video monitoring system of FIG. 2 toidentify a crossbore during utility line installation.

FIG. 3C is a schematic process view illustrating a third step of theexemplary method of using the video monitoring system of FIG. 2 toidentify a crossbore during utility line installation.

FIG. 3D is a schematic process view illustrating a fourth step of theexemplary method of using the video monitoring system of FIG. 2 toidentify a crossbore during utility line installation.

FIG. 4 is a schematic view of a downhole portion of the video monitoringsystem, including an adapter assembly connected to a drill string forutility line installation.

FIG. 5 is a side view of a product connection portion of the adapterassembly.

FIG. 6 is a cross-section view of the product connection portion, takenalong line 6-6 of FIG. 5.

FIG. 7 is an end view of the product connection portion of FIGS. 5-6.

FIG. 8 is a cross-section view of the product connection portion, takenalong line 8-8 of FIG. 7.

FIG. 9 is a detail view of a first end of the product connection portionas shown in FIG. 6.

FIG. 10 is a detail view of a second end of the product connectionportion as shown in FIG. 6.

FIG. 11 is a schematic view of a downhole portion of a multi-sourcemonitoring system, including an adapter assembly connected to a drillstring for utility line installation.

FIG. 12 is a wiring diagram of an EM sensor housing of the adapterassembly of FIG. 11.

FIG. 13 is a side view of an EM sensor housing of an alternateconstruction adapted to function also as a product connection portion ofthe adapter assembly.

FIG. 14 is a cross-section view of the EM sensor housing, taken alongline 14-14 of FIG. 13.

FIG. 15 is a detail view of a first end of the EM sensor housing asshown in FIG. 14.

FIG. 16 is a detail view of an antenna portion of the EM sensor housingas shown in FIG. 14.

FIG. 17 is a perspective view of an antenna portion of the EM sensor.

FIG. 18 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich a multi-device housing is provided.

FIG. 19 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich power to downhole monitoring device(s) is provided via one tracerwire and one wire from the drill string.

FIG. 20 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich power to downhole monitoring device(s) is provided via two wiresfrom the drill string.

FIG. 21 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich power to downhole monitoring device(s) is provided via one tracerwire and conductive utility line product being installed in theborehole.

FIG. 22 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich only an electromagnetic sensor is provided.

FIG. 23 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich an electromagnetic sensor is provided, along with at least oneadditional sensor, such as a strain gauge and/or pressure transducer.

FIG. 24 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich a camera is provided along with an electromagnetic sensor and atleast one additional sensor, such as a strain gauge and/or pressuretransducer.

FIG. 25 is a schematic view of a downhole portion of a monitoringsystem, according to another embodiment of the present disclosure, inwhich a camera is provided along with at least one additional sensor,such as a strain gauge and/or pressure transducer.

DETAILED DESCRIPTION

Before any embodiments of the present invention are explained in detail,it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thefollowing drawings. The invention is capable of other embodiments and ofbeing practiced or of being carried out in various ways.

FIG. 1 illustrates a basic system for horizontal directional drilling(HDD), including a HDD machine 100 operable to perform trenchless,directional-controlled underground drilling between two points, e.g.,for utility installations, such as gas lines. A plurality of drill rodassemblies are sequentially connected end-to-end on the HDD machine 100to form a drill string. The drill string is driven into the ground bythe HDD machine 100. At the end of the drill string is a drill head 104having a rotating drilling tool or drill bit. The drill head 104 caninclude electronics (e.g., gyroscopic sensor(s), a data relay receiver,a beacon, a steering mechanism) for tracking and/or steering the drillhead underground, and a wireline within the drill string connects thedrill head electronics to the HDD machine 100 during operation. The HDDmachine 100 includes a plurality of mechanical systems operable toassemble and disassemble a drill string and operable to plunge andretract the drill string into and out of the ground in a direction thatis at least partially horizontal with respect to the ground. In thisway, the HDD machine 100 can direct the drill head 104 to avoid anexisting underground utility installation, e.g., a pre-existing stormsewer 108, that is known to the HDD machine operator. However, thereremains the possibility of the HDD drill head 104 intersecting anotherunderground utility installation 110, resulting in a “crossbore.” Theother underground utility installation 110 may be unknown to theoperator, or known to the operator, but may not be avoided due tolimited positional accuracy of the location information and/or steeringcapability of the drill head 104, especially in locations where manyutilities are buried in close proximity to each other. Video data from adownhole camera may be used to inspect for crossbores. However, such asystem has the propensity to add significant time and expense to thedrilling process. For example, even if a camera is coupled to the drillhead 104 at the exit pit and used to observe downhole conditions duringpullback operation (retraction of the drill string, along with attachedutility product, toward the HDD machine 100), there is a need to unfurla long length of costly camera cable from a reel, and the camera cablemust then also be retracted from the bore after the utility product isinstalled. Meanwhile, other systems may record information to memorythat is downhole or may wirelessly transmit data to a processor on theground, but these solutions present drawbacks of not offering real timeinformation, or having real time information that is limited by wirelessconnection capability.

As shown in FIG. 2, an improved observation or monitoring system andmethod for providing real time downhole observation data can be providedvia utilization of tracer wires 120 and power line communication (PLC).PLC refers to the method of transferring electrical power and data forcommunication through the same network of wires from one end to theother end. Using PLC over the tracer wires 120 enables simultaneouspowering of an observation device 124 along with transmission of datato/from the device 124, in a half-duplex manner, on the same lines asthe power supply/distribution. The PLC may utilize Ethernet protocol. Inthe illustrated construction, the observation device 124 is a camera(e.g., digital Ethernet camera) such that the system is provided as avideo monitoring system. The camera 124 allows direct observation of theborehole, and this can be implemented for providing real time upholevideo monitoring, although the video data may also be recorded andsaved. Details relating to the camera 124, including lenses, circuitboards, and lights, among other aspects, may be similar in many respectsto those disclosed in U.S. Pat. Nos. 9,651,711 and 9,399,910, the entirecontents of which are incorporated by reference herein. The tracer wires120 are simple conductors, insulated and rated for direct burial, thatare installed alongside the utility line to remain underground along theutility line for later use in locating or “tracing” the utility linefrom ground level. A tracer wire is conventionally installed along autility line, exclusively for the purpose of enabling detection by anelectromagnetic probe after the installation is complete. However, asdetailed below, using a pair of tracer wires 120 as power linecommunication lines during utility installation to power the camera 124and send/receive camera data, several advantages are realized. Thesystem includes an uphole module 128 and a downhole module 132 atopposite ends of the tracer wires 120. The tracer wires 120 can be anuntwisted pair of insulated conductors, although use of a twisted pairof conductors is also contemplated. Further, the tracer wires 120 can beprovided as separate, loose wires or alternately, combined as twoisolated conductors within a common sheath, thus effectively forming asingle, two-conductor tracer wire 120′ (FIG. 2A). Although reference ismade in the description and drawings of tracer wires 120, certainaspects of the disclosure can include a system and method for using PLCfor real time borehole monitoring over a pair of insulated conductors(e.g., conductive product and/or drill string wireline) that are notsubsequently buried as tracer wires.

The uphole module 128 includes a power supply 136 operable to supplyelectrical power (e.g., DC at a predetermined voltage, which may bebetween 5V and 20V) to the camera 124 via the tracer wires 120.Electrical power is also supplied to an uphole PLC encoder 140A that isconfigured to communicate data (e.g., bi-directionally) over the tracerwires 120 that power the components of the downhole module 132. A firstdata communication line 144A connects the uphole PLC encoder 140A (e.g.,through Ethernet connections) to a computer 148, which may be a desktopcomputer, laptop computer, or other handheld computer device such as atablet or smartphone. The computer 148 may include or be connected witha monitor or display configured to display the data received over thetracer wires 120 from the camera 124 for viewing. The computer 148 mayalso include internal and/or external memory. Software loaded on thecomputer 148 may be executable to provide instructional commands to thecamera 124, which may include commands to change one or more settings ofthe camera 124, such as aperture and/or focal length. The software mayalso enable real time display of a view of the camera 124 whiledownhole. In addition to the camera 124, the downhole module 132includes another PLC encoder 140B (“child” or “slave” unit) that iscoupled to the uphole PLC encoder 140A (“parent” or “master” unit)through the pair of tracer wires 120. The downhole PLC encoder 140B isconnected to the camera 124 through a second data communication line144B (e.g., through Ethernet connections). As such, the downhole PLCencoder 140B is operable to receive the data output (e.g., video of asuitable format) of the camera 124 and transform the data fortransmission over the tracer wires 120 by PLC, as DC power is suppliedover the tracer wires 120 to the downhole module 132. In particular,both the camera 124 and the downhole PLC encoder 140B are energized byelectrical power supplied through the tracer wires 120 (e.g., throughouta pullback operation in which utility line product is installed into theborehole created by the HDD drill string).

FIGS. 3A to 3D illustrate a process for utility line installation, usingthe HDD machine 100, that takes advantage of the system of FIG. 2 toprovide real time video data transmission through tracer wires 120 to anuphole display for monitoring. FIG. 3A illustrates creation of a newborehole utilizing the drill head 104 coupled to the HDD machine 100through a drill string of numerous drill rods assembled sequentially atthe HDD machine 100. Conventional HDD steering techniques allow theoperator(s) to navigate the drill head 104 around a pre-existingunderground utility installation 108 between the entry and exit points,such as pits. Unbeknownst to the operator(s), the drill head 104 hasintersected another underground utility installation 110. At the exitpit, an adapter assembly 160 is coupled to the drill head 104 forattaching utility line 164 and the tracer wires 120 to be installed intothe borehole. The HDD machine 100 is operated to pull the utility line164 and the tracer wires 120 through the borehole from the exit pit tothe entry pit. The downhole PLC module 132, including the camera 124, isintegrated with or carried by the adapter assembly 160. As detailedfurther below, the camera 124 is rear-facing. That is, an image sensorand/or lens of the camera 124 is pointed opposite to the direction oftravel as the utility line 164 and the drill string are pulled backtoward the HDD machine 100. Thus, the camera 124 can still observe thepertinent surroundings for identifying a crossbore, but is lesssusceptible to gathering or impacting debris within the borehole.Because real time video data is transmitted uphole, the existence of acrossbore, e.g., at 110, can be identified in real time. During thepullback operation, an operator can log or mark the location of thecrossbore for future reference. This is illustrated by placement of theflag marker 170 in FIG. 3B. At completion of pullback, the drill head104 and the adapter assembly 160 can be disassembled adjacent the entrypit (FIG. 3C). In particular, the adapter assembly 160 containing thedownhole PLC module 132 is disconnected from the tracer wires 120, whichare buried in the borehole along the installed utility line 164.Further, the uphole PLC module 128, which may be located adjacent theexit pit, is also disconnected from the tracer wires 120. Theinstallation is then complete, albeit with the noted crossbore. Nofurther operations of the HDD machine 100 and drill string are necessarythrough the borehole following the installation of the utility line 164and the tracer wires 120 with the camera-enabled adapter assembly 160.Thus, workers and/or equipment (including the HDD machine 100 and/or thePLC modules 128, 132) can immediately leave the worksite as shown inFIG. 3D, while an excavation commences for rectifying the crossbore at110.

FIG. 4 illustrates a downhole portion of the video monitoring system asconnected to the drill string, in particular the adapter assembly 160connected between the drill head 104 and the utility line 164 beinginstalled. The adapter assembly 160 shown in FIG. 4 includes a pair ofseparate housings 174, 178 secured by multiple electrically-insulatedhigh-strength conductors 180. From the left side of FIG. 4 where thedrill head 104 is shown, the first housing 174 of the adapter assembly160 is the camera housing supporting the camera 124. A first end of thecamera housing 174 includes a connection structure for attachment withthe drill head 104, e.g., through a linkage 184, which may includeshackles, swivels, links, and/or rings. The camera 124 is positioned atthe second end of the camera housing 174 so as to view opposite thepullback direction and toward the second housing 178, which serves as acamera target and product connection portion of the adapter assembly160, as it makes a secure connection (e.g., via swage, eye bolt, orother connection structure as shown in broken lines in FIG. 5) to theutility line product 164 being installed. Power line communication istransmitted through the tracer wires 120 to the product connectionportion 178 of the adapter assembly 160 and through theelectrically-insulated high-strength conductors 180 to the camerahousing 174.

With further reference to FIGS. 5-10, the product connection portion 178includes a central housing body 188 (e.g., cylindrical-shaped body) andfirst and second end caps 190, 192 secured at opposite ends of thehousing body 188. The end caps 190, 192 can be connected directly to thehousing body 188, directly to each other (without a separate housingbody 188), or through respective threaded adapters 194 as shown. Some orall of these parts of the product connection portion 178 may beconstructed of anodized aluminum, among other metals or materials. Thefirst end cap 190, shown in greater detail in FIG. 9, establishesmechanical connections with the high-strength conductors 180. Thehigh-strength conductors 180 can be wire rope (e.g., steel, particularlystainless steel), commonly referred to as “aircraft cable,” and theconstruction of the aircraft cable can be what is known as a 7×19, whichis 7 groups of 19 strands per group, in some embodiments, although otherconstructions may be utilized in other embodiments. Each high-strengthconductor 180 can have a rope portion that is covered in insulation(e.g., PVC coating) and a fitting portion 196 at the end thereof. Thefitting portion 196 can be a steel sleeve having one or more threadedportions configured for clamping engagement with the end cap 190. Inparticular, an exterior nut 200 can be threaded onto the fitting portion196 on an outside of the end cap 190, and one or more interior nuts 202,204 can be threaded onto the fitting portion 196 on an inside of the endcap 190. Between the exterior 200 and interior 202, 204 nuts, thefitting portion 196 defines a shank or shaft that extends through athrough hole 206 of the end cap 190 and an insulator bushing 208 (e.g.,PEEK plastic) positioned therein. The exterior nut 200 compresses aflange portion of the insulator bushing 208, or another seal member,against an exterior face of the end cap 190 to seal the through hole206. An additional seal ring 212 (e.g., O-ring) may be provided alongthe interior of the through hole 206, between the end cap 190 and theinsulator bushing 208. It is noted that the fitting portion 196 iselectrically conductive in order to transmit power and data between thewire rope portion and the interior of the product connection housing178. An exterior part of the fitting portion 196, along with theexterior nut 200 in some constructions, may be at least partiallycovered or wrapped in insulating material such as PTFE (e.g.,heat-shrink). Such insulating material may also be provided on theexterior surface(s) of the end cap 190, although the end cap 190 iselectrically isolated from the high-strength conductors 180 by therespective insulator bushings 208.

Turning to the inside of the endcap 190, a washer 216 constructed ofinsulating material (e.g., PEEK plastic) is situated between theinterior end of the end cap 190 and the first interior nut 202. Thewasher 216 is arranged to be compressed for the transfer of load fromthe interior end of the high-strength conductor 180 to the end cap 190when the drill string is pulled back toward the HDD machine 100. Similarconnections (not shown) may be made between the high-strength conductors180 and the camera housing 174 (e.g., an end cap thereof). Each of thecamera and product connection housings 174, 178 further house internalelectrical conductors, including wires and connections for example, thatare non-load-bearing, such that the pullback loads are borne exclusivelyby the housings 174, 178 and the interconnecting high-strengthconductors 180. As shown in FIG. 9, a pair of internal electricconductors 220 (e.g., insulated wires) are coupled to the interior endsof the high-strength conductors 180, respectively. The internalconductors 220 can be connected to the respective high-strengthconductors 180 directly by wrapping a wire end into or around thefitting portion 196. In some constructions, each internal conductor 220at its end further includes a connector 224, for example, in the form ofa tab or ring terminal as shown. The connector 224 is placed between theinterior nuts 202, 204 and clamped therebetween. The connections betweenthe high-strength conductors 180 and the first end cap 190 are permanentin that they need not be connected and disconnected on the work site, oreven between separate uses at distinct work sites. Rather, onceassembled, the product connection housing 178 is not designed to requireroutine disassembly or service. Likewise, the entire adapter assembly160 need not be assembled and disassembled during the course of a fullprocess of use, other than making connections with the drill head 104 onone end, and the utility line 164 and tracer wires 120 at the secondend.

As each utility line installation in which the adapter assembly 160 isused requires the attachment and subsequent detachment of the tracerwires 120, the second end cap 192 of the product connection housing 178is adapted to facilitate efficient handling of the same. As shown inFIG. 10, the internal conductors 220 extend from their first ends at thehigh-strength conductors 180, through respective pass-through screws230, to second ends that terminate at a connector 234. The internalconductors 220 can each be in electrically conductive contact with theconnector 234, and fixed or bonded thereto, e.g., by epoxy or othermeans. By epoxy or other means, a permanent or semi-permanent, sealedconnection is established such that the internal conductors 220 and theinside of the product connection housing 178 is sealed from thesurrounding environment at the connector 234. Each connector 234 ishoused in a corresponding cavity 236 in the second end cap 192, and iselectrically isolated therefrom by an interstitial insulator 240, forexample a rubber sleeve or tube. The insulator 240 can be compressedinto the cavity 236 when the pass-through screws 230 are installed(i.e., by threading into apertures on the interior surface of the secondend cap 192). At the bottom of each cavity 236, opposite the screws 230,there may be provided washers 244 of silicone or another similarmaterial, providing a clearance or interference fit with the exteriorsurfaces of the respective tracer wires 120. As shown in FIGS. 7 and 8,access passages 248 are formed in the second end cap 192, from aperipheral or outer radial surface, to provide tool access (e.g., for ascrewdriver, hex key, etc.) for reaching a screw 252 that pinches orclamps the end of the tracer wire 120 to the connector 234, establishingmechanical and electrical connection therewith. The two access passages248 can be provided parallel to each other on the same side of thesecond end cap 192, so that the technician need not reorient the productconnection housing 178 when coupling or decoupling the pair of tracerwires 120. On the exterior of the second end cap 192 between the twotracer wires 120 is a blind hole 256 (e.g., threaded), as shown in FIGS.6, 7 and 10, provided for securement of an eye bolt or other structureused to make the connection with the utility line product 164.

FIGS. 11-17 relate to an improved observation or monitoring system, andindividual portions thereof, configured to provide real time downholeobservation data via utilization of tracer wires 120 for datatransmission, which in some constructions may be both data and powertransmission via power line communication (PLC). Using PLC over thetracer wires 120 enables simultaneous powering of multiple observationdevices 124, 324 along with transmission of data to/from the devices124, 324, in a half-duplex manner, on the same lines as the powersupply/distribution. However, it should be explicitly noted that someaspects of the disclosure may provide data transmission over the tracerwires 120, separate from electrical power supply to the device(s), whichmay instead be provided by other means, e.g., on-board battery(ies).Except as noted, details of the system components, andoperations/methods thereof can be similar to the above-described videomonitoring system. As such, reference can be made to the abovedescription for such details, while the additional description below isfocused upon features not already disclosed above. Like referencenumbers are used where appropriate for like components. In theillustrated construction, the first observation device 124 is a camera(e.g., digital Ethernet camera) such that the system is provided as avideo monitoring system, for providing real time uphole video monitoringin accordance with the first embodiment disclosed herein. However, thesystem can be a combined video and electromagnetic monitoring system, asthe second device 324 can be provided as an electromagnetic (EM) sensorthat is independently able to observe the borehole during pullback. Insome constructions, the EM sensor 324 is a more cost effective and lesscomplex solution as compared to ground penetrating radar. However, inother constructions, the EM sensor 324 operates to detect timedreflected radio waves such that it operates as a nearfield radar sensor.

The electromagnetic (EM) sensor 324 includes an antenna arrangement andcircuitry configured to detect changes in one or more antennaperformance characteristics indicative of a crossbore. As shown, the EMsensor 324 can include a first antenna 300 operable as a transmitter foremitting EM radiation into the surrounding borehole, and a secondantenna 304 operable as a receiver for receiving EM radiation. Thecircuitry operatively coupled with the antenna arrangement of the EMsensor 324 controls the emission of EM radiation from the first antenna300 and interprets the signals from the second antenna 304 in order tocreate a borehole map, or “see” the borehole, e.g., in order to detect acrossbore. For example, the EM sensor 324 can detect a large nearfieldreflection caused by the property change along the borehole, changes incoupling between antennas 300, 304, and/or how well energy is coupledfrom the antenna arrangement to the media forming the borehole. In someconstructions, the receiving antenna 304 records a large amplitude bloomfrom the change in permittivity between soil and void upon passage by acrossbore. Crossbore detection by the EM sensor 324 utilizes changes inantenna performance, rather than radar per se, as no imaging orreflected signals are used (e.g., no timed reflected signal is measured,or is range data available). Further details of the EM sensor 324,including the construction and usage of data can be found in PCT PatentApplication Publication No. WO 2018/049024 assigned to VermeerManufacturing Company and Merlin Technology, Inc., or U.S. PatentApplication Publication No. 2016/0265347 assigned to The Charles MachineWorks, Inc. and Louisiana Tech University Research Foundation, theentire contents of each of which are incorporated by reference herein.

With reference to FIG. 11, a downhole portion of the monitoring systemincludes an adapter assembly 360 connected between the drill head 104and the utility line 164 being installed. The adapter assembly 360 shownin FIG. 11 includes a pair of separate device housings 174, 308 and athird housing 178 that acts as the product connection portion of theadapter assembly 360 by making a secure connection (e.g., via swage, eyebolt, or other connection structure) to the utility line product 164being installed. From the left side of FIG. 11 where the drill head 104is shown, the first housing 174 is the camera housing supporting thecamera 124. The second device housing 308 is the EM sensor housing, orantenna housing, supporting the EM sensor 324. As such, the EM sensorhousing 308 can include at least one antenna window 310 transmissive tothe EM radiation sent/received by the EM sensor 324. The EM sensorhousing 308 is secured to each one of the camera housing 174 and theproduct connection portion 178 by respective sets of high-strengthconductors 180. As in the preceding embodiment, the first end of thecamera housing 174 includes a connection structure for attachment withthe drill head 104, e.g., through a linkage 184, which may includeshackles, swivels, links, and/or rings, while the camera 124 ispositioned at the second end so as to view opposite the pullbackdirection. As described with further reference to FIG. 12, power linecommunication (PLC) is transmitted through the product connectionportion 178 of the adapter assembly 160, through a first set of thehigh-strength conductors 180 to the EM sensor housing 308, and thenthrough a second set of the high-strength conductors 180 to the camerahousing 174.

As shown in FIG. 12, the two antennas 300, 304 are contained within theEM sensor housing 308, along with an electronic control subassembly 312.The electronic control subassembly 312 can include or be in the form ofone or more circuit boards, among other elements. The electronic controlsubassembly 312 can include a downhole PLC encoder 140C for the EMsensor 324. The PLC encoder 140C is in communication with an uphole PLCencoder, power supply, and computer/monitor forming an uphole module, asdescribed above with reference to the embodiment of FIG. 2. The downholePLC encoder 140C is operatively connected through the electronic controlsubassembly 312 with an EM signal processor circuit 316, which in turnis connected to the two antennas 300, 304 through respective antennaconnection wires or cables 320, 322. The antennas 300, 304 includerespective antenna shells 326, 328 having apertures 330, 332 for passageof PLC power/signal, along internal electric conductors 220 between thehigh-strength conductor pairs 180 on opposite ends of the EM sensorhousing 308. The aperture 330 in the first antenna shell 326 may alsoreceive the antenna connection wire 322 for passage to the secondantenna 304. In further embodiments, additional instruments and/orsensors are provided in the EM sensor housing 308, and each of these mayalso be connected with the uphole module via PLC through the electroniccontrol subassembly 312. Examples include but are not limited to: straingauge(s), pressure transducer(s), temperature sensor(s), and/or groundpenetrating radar. Such instruments and/or sensors may be used incrossbore detection and/or for separate purposes.

Although the monitoring system as shown in FIG. 11 incorporates aproduct connection portion 178 that is distinct from the device housings174, 308, it is also conceived to incorporate features of the productconnection portion 178 into the nearest device housing, in this case theEM sensor housing 308. FIGS. 13 and 14 illustrate such an embodiment ofan EM sensor housing 308A.

The EM sensor housing 308A as shown in FIGS. 13 and 14 includes acentral housing body 388 (e.g., cylindrical-shaped body) that isentirely or partially transmissive to the EM signals of the EM sensor324 so as to form an antenna window(s). The EM sensor housing 308Afurther includes first and second end caps 190, 192 secured at oppositeends of the housing body 388. The end caps 190, 192 can be connecteddirectly to the housing body 388, directly to each other (without aseparate housing body 388), or through respective threaded adapters 194as shown. Some or all of these parts of the EM sensor housing 308A maybe constructed of anodized aluminum, among other metals or materials.The first end cap 190, shown in greater detail in FIG. 15, establishesmechanical connections with the high-strength conductors 180 that extendto the camera housing 174. The construction of the first end cap 190,the high-strength conductors 180, and the connection therebetween can besimilar to that described above for the first end cap 190 of theproduction connection portion 178. As such, like reference numbers areused, and the above description is hereby referenced so as to avoidredundant description.

As shown in FIGS. 14 and 15, a first pair of internal electricconductors 220A (e.g., insulated wires) are coupled to the interior endsof the high-strength conductors 180, respectively. The internalconductors 220A can be connected to the respective high-strengthconductors 180 directly by wrapping a wire end into or around thefitting portion 196. In some constructions, each internal conductor 220Aat its end further includes a connector 224, for example, in the form ofa tab or ring terminal as shown. The connector 224 is placed between theinterior nuts 202, 204 and clamped therebetween. The connections betweenthe high-strength conductors 180 and the first end cap 190 are permanentin that they need not be connected and disconnected on the work site, oreven between separate uses at distinct work sites. Rather, onceassembled, the EM sensor housing 308A is not designed to require routinedisassembly or service. Likewise, the entire adapter assembly 360 neednot be assembled and disassembled during the course of a full process ofuse, other than making connections with the drill head 104 on one end,and the utility line 164 and tracer wires 120 at the second end. Thefirst pair of internal conductors 220A connect to the electronicscontrol subassembly 312 (e.g., the PLC encoder 140C thereof), which inturn connects to the tracer wires 120 via a second pair of internalelectrical conductors 220B (FIG. 14). In other constructions, PLC may betransmitted between the tracer wires 120 and the high-strengthconductors 180 by a single pair of internal electrical conductors thatextend external to the electronics control subassembly 312, which may bepowered by jumper lines tapped from the pair of internal electricalconductors as shown in FIG. 12. The second pair of internal electricalconductors 220B pass through the apertures 330, 332 of the respectiveantenna shells 326, 328. The apertures 330, 332 can be positionedoff-center with respect to a central axis A

As described above with respect to the adapter assembly 160, the secondend cap 192 is configured for the attachment and subsequent detachmentof the tracer wires 120 (FIG. 14). The second pair of internalconductors 220B extend through the respective antenna shell holes 330,332 to the respective pass-through screws 230 on the inside surface ofthe second end cap 192. As shown in FIGS. 16 and 17, each antenna shell326, 328 can include two shell halves fastened together with a fastenerassembly such that the antenna coil or element is located therebetween.From the second antenna shell 328, the internal conductors 220B extendto the connectors 234 to be fixed or bonded thereto, e.g., by epoxy orother means. The second end cap 192 may have the same construction asdescribed above with respect to FIG. 10, including for example, theinsulator 240, washers 244, and access passages 248 for tightening orloosening screws (not shown) that pinch or clamp the ends of therespective tracer wires 120 to the connector 234. Further, as mentionedabove, the second end cap 192 can include a structure such as a blindhole 256 (e.g., threaded) for securement of an eye bolt or otherstructure used to make the connection with the utility line product 164.

FIG. 18 illustrates yet another embodiment of an adapter assembly 460for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 460 can be similar to the adapter assembly 360 as shown in FIG.11, including the camera 124 and the EM sensor 324, among other possibleinstruments or sensor as noted above. However, the camera 124 and the EMsensor 324 are packaged together in a single housing 474, ormulti-device housing. The multi-device housing 474 has a first endcoupled to the drill head 104 and a second opposite end coupled to theproduct connection portion or housing 178 through the high-strengthconductors 180. The multi-device housing 474 contains the electroniccontrol subassembly 312 and all hardware for establishing PLC with thecamera 124 and the EM sensor 324, among other possible instruments orsensors. The hardware can include multiple PLC encoders as part of adownhole module of a multi-device borehole monitoring system, thedownhole module being connected to an uphole module as described aboveand illustrated in FIG. 2.

FIG. 19 illustrates yet another embodiment of an adapter assembly 560for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 560 can be similar to the adapter assembly 360 as shown in FIG.11, including the camera 124 and the EM sensor 324, among other possibleinstruments or sensor as noted above. However, PLC transmission can usea combination of a single tracer wire 120 alongside the utility lineproduct 164, and an additional electrical connection such as a wire 520extending, with slack so as not to bear the pullback loads, through oralongside the linkage 184 to the camera housing 174. The wire 520 can bea wireline that extends within the drill string to the drill head 104for locating and/or steering the drill head 104, or alternately the wire520 can be a separate wire coupled to the internal wireline. In bothcases, the wire 520 is referred to as drill string wire, and the drillhead 104 includes an exit port for connection of the drill string wirewith the adapter assembly 560. Thus, the camera housing 174 may have anend cap configured for the connection or passage of the drill stringwire 520 to an interior thereof, similar to the second end cap 192 thatis configured to connect with the tracer wires 120. As illustratedschematically in FIG. 19, the PLC power is divided such that thepositive line comes to the adapter assembly 560 from one end (e.g., exitpit side), and the ground line comes to the adapter assembly 560 fromthe opposite end (e.g., the HDD or entry pit side). Nonetheless, thesetwo separate power lines provide the means for PLC to/from both thecamera 124 and the EM sensor 324, among other instruments or sensors.Thus, only half as much tracer wire is needed as compared to precedingembodiments, although the tracer wire that is used is used both duringand after installation. As a side-effect of this configuration, one ofthe high-strength conductors 180 between the EM sensor housing 308 andthe product connection portion 178 is not in fact utilized as aconductor for PLC. In yet another construction, the drill string wire520 is one of two drill string wires that provide the PLC communicationto the downhole instruments/sensors.

FIG. 20 illustrates yet another embodiment of an adapter assembly 660for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Thisembodiment is a variation of the embodiment of FIG. 19 that providesboth the positive and ground conductors for the PLC to the downholedevice(s) via multiple drill string wires 620 (e.g., multiple conductorwires within a cable). As such, the tracer wire(s) 120 is passive duringinstallation of the utility line product 164 and only usedpost-installation to trace the location of the buried utility line. Dueto this configuration, the high-strength conductors 180 between theproduct connection portion 178 and the EM sensor housing 308 are not infact utilized as conductors for PLC, nor is PLC transmission conductedthrough the product connection portion 178. As such, these high-strengthconductors 180 may be coupled with simplified connections, and in someconstructions, need not even be provided as isolated conductors.

FIG. 21 illustrates yet another embodiment of an adapter assembly 760for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 760 can be similar to the adapter assembly 360 as shown in FIG.11, including the camera 124 and the EM sensor 324, among other possibleinstruments or sensor as noted above. However, PLC transmission can usea combination of a single tracer wire 120 alongside the utility lineproduct 164, and the utility line product itself (e.g., a conductivemetallic utility line product). Thus, two tracer wires are not required.A portion of the product connection portion 178 is configured toestablish an isolated conductive path between the utility line product164 and one of the high-strength conductors 180 (i.e., the one notconnected to the tracer wire 120).

FIG. 22 illustrates yet another embodiment of an adapter assembly 860for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 860 can include a housing 308A containing the EM sensor 324.The housing 308A may provide product connection, or another housing forproduct connection may be provided. The adapter assembly 860 includesonly the EM sensor 324 for downhole sensing. As such, crossboredetection may be provided (e.g., through PLC as described above) solelyby EM sensing—without any camera.

FIG. 23 illustrates yet another embodiment of an adapter assembly 960for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 960 can include a housing 308A containing the EM sensor 324.The housing 308A may provide product connection, or another housing forproduct connection may be provided. The adapter assembly 960 includes nocamera, but may include (in the same housing 308A or another housing) atleast one additional sensor that communicates through PLC, such as astrain gauge 340 and/or pressure transducer 350. The pressure transducer350 may be exposed to borehole pressure (i.e., outside the housing308A), and in some constructions may be utilized in crossbore detection.In particular, “wet” drilling techniques utilize pressurized drillingmud in the borehole, and a pressure drop at a particular location mayindicate a void such as a crossbore. Additional details regarding thepackaging and/or data usage of the pressure transducer 350 can be foundin U.S. Pat. No. 9,664,027 assigned to Merlin Technology Inc., theentire contents of which are incorporated by reference. As such,crossbore detection may be provided (e.g., through PLC as describedabove) without any camera, whether through the EM sensor 324, thepressure transducer 340, or both. The strain gauge 340 (and otheroptional instruments such as a temperature sensor) may be operatedduring pullback, either in conjunction with crossboremonitoring/detection or for purposes unrelated to crossbore detection.

FIG. 24 illustrates yet another embodiment of an adapter assembly 1060for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 1060 can include a housing 174 containing the camera 124 andthe EM sensor 324, along with at least one additional sensor thatcommunicates through PLC, for example a strain gauge 340 and/or pressuretransducer 350, as described in detail with respect to FIG. 23.

In a system having the setup as shown in FIG. 24, the EM sensor 324 canprovide a preliminary warning, so that an operator is notified to moreclosely observe the data supplied from the camera 124. While boring, ifthe EM sensor 324 generates a warning at the time the housing 174 of theadapter assembly 1060 passes through something, that area becomesvisible to the camera 124 just shortly thereafter. The housing 178 inthis instance provides a consistent reference visible to the camera 124to help in understanding the image.

FIG. 25 illustrates yet another embodiment of an adapter assembly 1160for a downhole portion of a borehole monitoring system connected betweenthe drill head 104 and the utility line 164 being installed. Unlessotherwise noted, details of the components and method(s) of operationconform to the description of the preceding embodiment(s), and likereference numbers are used for like parts. In particular, the adapterassembly 1160 can include a housing 174 containing the camera 124, alongwith at least one additional sensor that communicates through PLC, forexample a strain gauge 340 and/or pressure transducer 350, which may ormay not be configured for crossbore detection. The adapter assemblyhousing 174 does not include an EM sensor. However, the EM sensor 324can be provided in a separate housing (e.g., the product connectionhousing 178 as illustrated) to operate for borehole observationaccording to the preceding description. As illustrated in FIG. 25, thisembodiment can provide a system in which the camera 124 is able tovalidate the bore hole condition at the EM sensor 324 since the camerain the housing 174 is able to see the housing 178 where the EM sensor324 is located in the adapter assembly 1160. Thus, the camera 124 isable to validate the data generated by the EM sensor 324.

Changes may be made in the above methods and systems without departingfrom the scope hereof. Also, aspects of various embodiments may becombined unless expressly prohibited. It should thus be noted that thematter contained in the above description or shown in the accompanyingdrawings should be interpreted as illustrative and not in a limitingsense. The following claims are intended to cover all generic andspecific features described herein, as well as all statements of thescope of the present method and system, which, as a matter of language,might be said to fall therebetween.

What is claimed is:
 1. A horizontal directional drilling methodcomprising: operating a horizontal directional drilling machine to powera drill string terminating at a drill head to create an undergroundborehole extending at least partially horizontally between an entrypoint and an exit point; attaching a utility line and a pair ofinsulated wires to the drill string at the exit point; further attachingan observation device to the drill string, the observation deviceconnected with an uphole module via power line communication over thepair of insulated wires; performing pullback of the drill string, withthe utility line, the pair of insulated wires, and the observationdevice connected thereto, back toward the entry point with thehorizontal directional drilling machine; and displaying data from theobservation device on the uphole module during pullback of the drillstring, wherein, upon completion of the pullback of the drill string,the pair of insulated wires are decoupled from the drill string andburied in the underground borehole as tracer wires alongside theinstalled utility line.
 2. The horizontal directional drilling method ofclaim 1, wherein the observation device is a camera, and the datadisplayed on the uphole module during pullback of the drill string isreal time video data of the underground borehole.
 3. The horizontaldirectional drilling method of claim 2, wherein the camera is attachedto the drill string to view in a direction opposite a direction of thepullback of the drill string.
 4. The horizontal directional drillingmethod of claim 1, further comprising identifying via the data from theobservation device on the uphole module a crossbore along theunderground borehole.
 5. The horizontal directional drilling method ofclaim 1, wherein the observation device is a first observation device,the method further comprising attaching to the drill string a secondobservation device configured to collect a second type of data, thesecond observation device connected with the uphole module via powerline communication over the pair of insulated wires; and displaying datafrom the second observation device on the uphole module during pullbackof the drill string.
 6. The horizontal directional drilling method ofclaim 5, wherein the second observation device is operated by energizinga first electromagnetic antenna to send an electromagnetic signal intothe borehole and receiving a reflected electromagnetic signal with asecond antenna.
 7. A horizontal directional drilling method comprising:operating a horizontal directional drilling machine to power a drillstring terminating at a drill head to create an underground boreholeextending at least partially horizontally between an entry point and anexit point; attaching a utility line and a pair of insulated wires tothe drill string at the exit point; further attaching an observationdevice to the drill string, the observation device connected with anuphole module via power line communication over the pair of insulatedwires; performing pullback of the drill string, with the utility line,the pair of insulated wires, and the observation device connectedthereto, back toward the entry point with the horizontal directionaldrilling machine; and displaying data from the observation device on theuphole module during pullback of the drill string, wherein theobservation device is a first observation device, the method furthercomprising attaching to the drill string a second observation deviceconfigured to collect a second type of data, the second observationdevice connected with the uphole module via power line communicationover the pair of insulated wires; displaying data from the secondobservation device on the uphole module during pullback of the drillstring; and transmitting the power line communication for both the firstand second observation devices from the pair of insulated wires througha product connection housing secured to the utility line and from theproduct connection housing through a pair of wire ropes to a devicehousing containing the first and second observation devices.
 8. Ahorizontal directional drilling method comprising: operating ahorizontal directional drilling machine to power a drill stringterminating at a drill head to create an underground borehole extendingat least partially horizontally between an entry point and an exitpoint; attaching a utility line and a pair of insulated wires to thedrill string at the exit point; further attaching an observation deviceto the drill string, the observation device connected with an upholemodule via power line communication over the pair of insulated wires;performing pullback of the drill string, with the utility line, the pairof insulated wires, and the observation device connected thereto, backtoward the entry point with the horizontal directional drilling machine;and displaying data from the observation device on the uphole moduleduring pullback of the drill string, wherein the observation device is afirst observation device, the method further comprising attaching to thedrill string a second observation device configured to collect a secondtype of data, the second observation device connected with the upholemodule via power line communication over the pair of insulated wires;displaying data from the second observation device on the uphole moduleduring pullback of the drill string; and transmitting the power linecommunication for both the first and second observation devices from thepair of insulated wires through a product connection housing secured tothe utility line and from the product connection housing through a firstpair of wire ropes to a first device housing containing the firstobservation device, and through a second pair of wire ropes to a seconddevice housing containing the second observation device.
 9. A horizontaldirectional drilling system comprising: a horizontal directionaldrilling machine; a drill string terminating at a drill head andconfigured to be driven by the horizontal directional drilling machineto create an underground borehole extending at least partiallyhorizontally between an entry point and an exit point; an adapterassembly configured to couple a utility line and a pair of insulatedwires to the drill string; an observation device configured to beattached to the drill string; and an uphole module connected with theobservation device via power line communication over the pair ofinsulated wires, wherein the pair of insulated wires are direct burialtracer wires configured to be installed alongside the utility line. 10.The horizontal directional drilling system of claim 9, wherein theobservation device is a camera operable to send video data of theunderground borehole over the pair of insulated wires for display at theuphole module during pullback of the drill string.
 11. The horizontaldirectional drilling system of claim 10, wherein the camera is orientedto view in a direction opposite a direction of the pullback of the drillstring.
 12. The horizontal directional drilling system of claim 9,wherein the pair of insulated wires are individually isolated conductorsencased in a common sheath.
 13. A horizontal directional drilling systemcomprising: a horizontal directional drilling machine; a drill stringterminating at a drill head and configured to be driven by thehorizontal directional drilling machine to create an undergroundborehole extending at least partially horizontally between an entrypoint and an exit point; an adapter assembly configured to couple autility line and a pair of insulated wires to the drill string; anobservation device configured to be attached to the drill string; anuphole module connected with the observation device via power linecommunication over the pair of insulated wires; a product connectionhousing coupled to the utility line and to the pair of insulated wires;a device housing containing the observation device and a power linecommunication encoder; and a pair of wire ropes extended between theproduct connection housing and the device housing to bear tensilepullback loads while transmitting power line communication between theproduct connection housing and the device housing.
 14. The horizontaldirectional drilling system of claim 13, further comprising a secondobservation device provided in a second device housing and configured tocollect a second type of data, the second observation device connectedwith the uphole module via power line communication over the pair ofinsulated wires; and a second pair of wire ropes extended between thedevice housing and the second device housing to bear tensile pullbackloads while transmitting power line communication between the devicehousing and the second device housing.
 15. The horizontal directionaldrilling system of claim 14, wherein the observation device is a cameraoriented to view in a direction opposite a direction of the pullback ofthe drill string, and wherein the second observation device includes anelectromagnetic sensor including a transmitter antenna operable to sendan electromagnetic signal into the borehole and a receiver antennaoperable to receive a reflected electromagnetic signal.
 16. Thehorizontal directional drilling system of claim 13, wherein theobservation device is a camera oriented to view in a direction oppositea direction of the pullback of the drill string, the horizontaldirectional drilling system further comprising a second observationdevice provided in the device housing with the camera.
 17. Thehorizontal directional drilling system of claim 16, wherein the secondobservation device includes an electromagnetic sensor including atransmitter antenna operable to send an electromagnetic signal into theborehole and a receiver antenna operable to receive a reflectedelectromagnetic signal.
 18. A horizontal directional drilling systemcomprising: a horizontal directional drilling machine; a drill stringterminating at a drill head and configured to be driven by thehorizontal directional drilling machine to create an undergroundborehole extending at least partially horizontally between an entrypoint and an exit point; a camera provided within an adapter assemblythat couples a utility line to the drill string for installation of theutility line into the borehole during pullback of the drill string,wherein the camera is oriented to view in a direction opposite adirection of the pullback of the drill string; and an uphole moduleconnected with the camera via power line communication over a pair ofinsulated wires, wherein the power line communication utilizes at leastone direct burial tracer wire that is connected to the drill string toextend along the utility line during pullback.
 19. A horizontaldirectional drilling system comprising: a horizontal directionaldrilling machine; a drill string terminating at a drill head andconfigured to be driven by the horizontal directional drilling machineto create an underground borehole extending at least partiallyhorizontally between an entry point and an exit point; an observationdevice provided within an adapter assembly that couples a utility lineto the drill string for installation of the utility line into theborehole during pullback of the drill string; and an uphole moduleconnected for data transmission with the observation device over a pairof direct burial tracer wires that are connected to the drill string toextend along the utility line during pullback.